.\"	$NetBSD: socketpair.2,v 1.23 2011/06/27 08:21:08 wiz Exp $
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.\"     @(#)socketpair.2	8.1 (Berkeley) 6/4/93
.\"
.Dd June 24, 2011
.Dt SOCKETPAIR 2
.Os
.Sh NAME
.Nm socketpair
.Nd create a pair of connected sockets
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/socket.h
.Ft int
.Fn socketpair "int d" "int type" "int protocol" "int *sv"
.Sh DESCRIPTION
The
.Fn socketpair
call creates an unnamed pair of connected sockets in
the specified domain
.Fa d ,
of the specified
.Fa type ,
and using the optionally specified
.Fa protocol .
The descriptors used in referencing the new sockets
are returned in
.Fa sv[0]
and
.Fa sv[1] .
The two sockets are indistinguishable.
.Pp
The
.Fa type
and
.Fa protocol
argument values are described in
.Xr socket 2 .
.Sh RETURN VALUES
A 0 is returned if the call succeeds, \-1 if it fails.
.Sh ERRORS
The call succeeds unless:
.Bl -tag -width Er
.It Bq Er EAFNOSUPPORT
The specified address family is not supported on this machine.
.It Bq Er EFAULT
The address
.Fa sv
does not specify a valid part of the
process address space.
.It Bq Er EMFILE
Too many descriptors are in use by this process.
.It Bq Er ENFILE
The system file table is full.
.It Bq Er EOPNOTSUPP
The specified protocol does not support creation of socket pairs.
.It Bq Er EPROTONOSUPPORT
The specified protocol is not supported on this machine.
.El
.Sh SEE ALSO
.Xr pipe 2 ,
.Xr read 2 ,
.Xr socket 2 ,
.Xr write 2
.Sh HISTORY
The
.Fn socketpair
function call appeared in
.Bx 4.2 .
.Sh BUGS
This call is currently implemented only for the
.Dv PF_LOCAL
domain.
